In media handling assemblies, particularly in printing systems, one problem often encountered is that certain media handling and conveying configurations are significantly noisier than others. FIG. 1 depicts a simplified view of a media path for an existing, or prior art, printing system 10. Media, usually paper 14, is transported from a media sheet source, typically a paper storage tray 12, onto a traditional nip roller based media transport 22 with nip releases. The leading edge 18 of the paper is acquired by the media transport feed nip rollers 22. The paper 14 is generally conveyed within the system in a process direction.
The media handling mechanism is a significant contributor to the print mode noise. As a sheet is fed from the paper tray 12, there are discrete events as its leading edge (LE) 18 and trailing edge (TE) 20 transition between guide surfaces 26, each having associated audible noise. In some printing systems, there may be additional guide surfaces beyond the two shown. For example, as the paper 14 first touches each guide surface 26, the paper makes a noise. There is also sliding contact between the paper surface 16 and the guide surfaces 26, as the paper moves across each guide surface, which is also a significant noise source. There is significant bending strain energy stored in the paper 14, and relatively high contact forces due to the small radii of curvature within the media path along which the paper moves. These factors have made attempts at noise reduction difficult.
In any printing system, and especially in a desktop product, its overall footprint and height need to be minimized. One outcome of this is a very compact media path in which sheets of paper 14 fed out of the paper tray 12 are forced around an approximately 35 mm diameter bend between the feed nip rollers 22 and the take-away roll (TAR) nip rollers 24.
A number of fixed guides 26 exist between the feed nip rollers 22 and the TAR nips 24, as well as an idler roll 28 on the inside of the bend. The design of these guides is a compromise between robust guidance of the paper LE 18 and control of the body and TE 20 of the paper 14. There is significant audible noise generated as the paper LE 18 transitions from one guide surface 26 to the next; as the paper LE 18 enters the TAR nip 24; as the body of the paper contacts and slides on the stationary guide surfaces 26; as the TE 20 transitions from the feed nip 22 to the next guide; and as the TE 20 transitions into the TAR nip 24. From there, the paper exits the TAR nip 24 and encounters downstream guides 26. A sample noise trace, taken by measurement during a test, is shown in FIG. 2.
The noise level in dBA of the FIG. 1 printer while feeding a sheet of paper is shown as the solid trace ‘Standard Print’ in FIG. 2. The dotted trace shows the noise level during a ‘dry cycle’ in which no paper is present. It is evident that there is significant audible energy due to the paper passing through the media path, and this has been associated with the media handling events described above. A variety of remediative methods and mechanisms have been devised and tested to reduce the overall noise level of paper and other media sheets passing through the media path, with limited success Improvements on the order of 1-3 dBA have been seen, but the goal of silencing by approximately 65 dBA has, until now, been elusive.
Accordingly, it would be desirable to provide an apparatus capable of elimination of stationary guide surfaces, thereby avoiding the problems associated with the prior art.